The present invention encompasses fabric bleaching compositions and processes adapted for use in an automatic dryer. More specifically, the process herein employs a solid, substantially dry, activated peroxygen bleach composition in an automatic clothes dryer to remove stains from fabrics. The bleach compositions are formulated to provide the requisite solubility in the limited amount of water available from the damp fabrics which are being dried.
Fabric treating processes and compositions designed to provide desirable functional and aesthetic benefits to fabrics are conventionally employed in a washing machine. Thus, fabric sizings and softening agents, fabric bleaches and brighteners, and the like, are most commonly formulated and provided as compositions designed for use either in an aqueous laundering liquor or in an aqueous rinse bath. More recently, the treatment of fabrics in an automatic clothes dryer has been shown to be an effective means for imparting desirable properties thereto. For example, it is becoming common to soften fabrics in an automatic clothes dryer rather than during the rinse cycle of a laundering operation.
U.S. Pat. No. 3,701,202 discloses a dispensing means for use in an automatic clothes dryer and suggests that fabrics may be softened, bleached, and otherwise desirably treated in the dryer. However, this patent relates only to a useful dispenser for fabric treatment compositions and does not disclose operable compositions which can be employed therein. U.S. Pat. No. 3,180,037 discloses a modified bleaching/drying apparatus.
The most familiar method for bleaching fabrics to remove stains, especially in the context of a home laundering operation, is to add an oxidizing bleach directly to the laundering liquor. Liquid hypochlorite solutions are most commonly employed, but solid peroxygen bleaches are also commerically available. Such bleaches are designed for addition to the laundering bath in conjunction with the detergent, and provide the desired bleaching action concurrently with fabric laundering.
While through-the-wash bleaching processes are effective in most instances, they do suffer from several inherent drawbacks. For example, the addition of either liquid or solid bleaches to the 10-21 gallons of water normally employed in an automatic washing machine substantially dilutes the bleach, thereby reducing its effectiveness. For this reason, the quantities of bleach employed in the laundering bath must necessarily be high to overcome the dilution effect. Moreover, certain stains can actually be "set" by oxidizing bleaches when used in combination with a detergent in an aqueous laundering bath. For example, blood stains and mineral stains can be darkened by some oxidizing bleaches and become more tenaciously affixed to the fabrics. In such instances, it is more desirable to remove these kinds of stains by washing in the absence of bleach, and to complete the laundering operation by a later bleaching step. Additionally, many oxidizing bleaches contain ingredients which are not compatible with certain components of laundry detergents. Undesirable interactions can ensue when such bleaches and detergents are commingled in the laundering liquor.
From the foregoing, it is seen that it would be desirable to provide a means whereby the bleach user could conveniently and effectively bleach fabrics other than in an aqueous laundering liquor.
It has now been found that solid bleaches, especially peroxygen bleaches, can be employed in the manner disclosed more fully hereinafter to bleach fabrics in an automatic clothes dryer. In a preferred mode, solid peroxygen bleaches are activated by means of certain additives and employed in an automatic dryer to provide substantial bleaching superiority over dry bleaching compositions employed in a laundering liquor.
Accordingly, it is an object of the present invention to provide compositions and processes designed to achieve through-the-dryer fabric bleaching.
It is another object herein to provide dryer-bleaching compositions especially adapted for use in conjunction with the limited amount of water available as a reaction medium in an automatic clothes dryer.
These and other objects are obtained herein as will be seen from the following disclosure.